First, did you notice that there is really no "V-curve," just noisy star sizes between 3.9 and 6.0 pixels?
Auto focusing expects to see a star size of 9 or more at the start, and dipping down to the smallest star size (which could be in the 2.0 to 2.5 pixel range if you had picked a camera with a good pixel scale, and when "seeing," is good. After the minimum, the star size rises again to a star size of 9 or above.
Either the focuser is mechanically slipping, and/or you need a much larger autofocusing EAF step size than the one which you have chosen. I see that you have given it a EAF step size (for auto focusing) that is 30 steps (for example., going from 2163 to 2133).
So, first check if your grub screws of the flexible coupler are tight. Remember that one of the grub screws have to be tighten against the flat surfaces of the EAF shaft. Torque that one down first with as much force as you can muster, and then tighten the other one on the round side of the shaft. Do the same thing at the rack and pinion focuser shaft if it too has a flat indentation.
Watch the curve after that, and if it is still not producing a V curve, increase the auto focus step size (not the manual focus step size) until you see the star sizes change.
Make sure you have completely loosen the focuser locking screw.